Reforge Blood of Isiset into Spirit if you ever find mana to be a problem.

I wouldn't take the advice to reforge everything to haste. Reforging crit to either mastery or haste is fine.

Try to keep your mastery a whole number (check your character sheet) via reforging, because there is no difference between 7.02 mastery and 7.98 mastery.

Really sick of people giving this terrible advice, it has been proven by EJs that Mastery scales to the .01% just like any other stat. OT, for a Holy Priest Mastery is pretty amazing, and Haste is kinda meh, id go for as much mastery as is humanly possible.

While my priest's gear isn't quite there -yet-, my plan is to get my haste to 9% (+3% from 3/3 Darkness), and after that I will stack mastery. My spirit is whatever will give me enough regen to gain the amount of mana my Heal uses, effectively making it free.

For reforging, you should take whatever stat you have too much of, or isn't very valuable (like crit) and reforge it to something you need.

If you want to make raiding content harder, turn off DBM. Voila! Your encounters will be much more challenging without bleeps and someone telling you to "run away, little girl."

Why are you reforging Mastery to Haste? Who gave you that advice? Mastery is your strongest stat as a Holy Priest. You do NOT reforge Mastery. You reforge all the Crit you can find to Mastery (or possible Haste if you think you need it), Haste to Mastery if you have enough Haste and that's it. You never reforge Mastery into anything.